PLANT MANAGEMENT/ AUTOMATION


Electric actuators installed for improved wellhead pressure control at shale gas production site


Overview Rotork’s customer produces shale gas and liquid hydrocarbons at the East Texas section of the Haynesville/Bossier shale gas formation. It is a Jurassic Period rock formation which covers large parts of South West Arkansas, North West Louisiana and East Texas.


The customers operations in the Haynesville basin, as well as its oil and gas assets in the nearby Eagle Ford and Permian-Delaware basins, contribute to the company producing 190,000 barrels of oil equivalent per day in Texas and Louisiana combined.


The Reason


A way of ensuring a tight well flow threshold to avoid over pressure in the main trunkline was required. If too much gas is extracted in a short period of time the reservoir can implode or cause ground fractures which water or gas can infiltrate leading to a loss in production.


The Solution Rotork’s customer has ordered IQTF actuators to carry out modulating duties on wellhead rotary non-rising choke valves at the site near the city of Lufkin.


Approximately 60 actuators have already been installed to control the flow and pressure of gas and condensate, a mixture of liquid hydrocarbons formed when pressure and temperature decrease as a result of well drilling. Two IQTF actuators have been installed on each well and more than 30 have also been ordered to hold in the customer’s inventory.


To maximise the lifespan of the wells, the customer is using two choke valves on each one to step pressure down from 10,000 psi to 1,200 psi. Shale gas is metered between the wellhead and midstream trunkline where it is transported to domestic supply customers as well as industries including LNG plants and power stations.


The remote location of the wells means a DC power supply using a solar system and battery pack is being used to power the IQTF actuators. This solution was


SEPTEMBER/OCTOBER 2019


specified as a more reliable option than hydraulic or pneumatic actuation as it avoids potential leakage common in hydraulic actuators. Texas also has plenty of sun to use as a source while electric actuators use less power than a hydraulic system.


The Results


The main reason for choosing electric actuators (IQTF, DC) was because the alternate offering of hydraulic actuators can be unreliable and very costly for maintenance. There also environmental issues should any failures occur resulting in spilt hydraulic oil on the earth.


IQTF DC are using renewable energy from solar panels charging batteries. Although this was a risk as it is a new technology and control philosophy it has proved to be extremely reliable and provides tight control tolerances which is better for when the pipeline gas is transferred into the main trunk line. This is because it provides better stability and reliability for custody transfer, pipeline pressure balancing, well stability and equipment reliability.


Rotork’s dedicated Sales staff spent several months with the customer to ensure the IQTF was the most fit for purpose product. Rotork Site Services


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also offered final commission and warranty, as well as support during initial testing and calibrating.


Engineered for choke and control valve applications, Rotork’s IQTF actuators can provide reliable flow control for oil and gas or process operations, capable of achieving accuracy to 0.3% and resolution to 0.1%. A highly accurate absolute position sensor can measure up to 22 output turns independent of electrical power.


About Rotork


Rotork is the market leading actuator manufacturer and flow control company that operates in any market where the flow of gases or liquids needs to be controlled. It has established manufacturing facilities, a global network of local offices and agents who can truly provide a worldwide service. You will be able to locally source Rotork’s products, supported by life-of- plant maintenance, repair and upgrade services.


For more information please contact: Sarah.Kellett@rotork.com www.rotork.com


Enquiry No. 21


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